It is well known in the multiple ratio transmission art that synchronizer mechanisms may be used to reduce shift time of all or some of the transmission gear ratios. It is also known that the shift effort required by a vehicle operator, i.e., force applied to a shift lever, may be reduced by use of synchronizer mechanisms of the self-energizing type. A prior art example of a pin-type synchronizer mechanism with self-energization may be seen by reference to U.S. Pat. No. 5,092,439, which is incorporated herein by reference.
The pin-type synchronizer mechanism disclosed in the above patent includes friction and jaw members for respectively synchronizing and positive clutching axially spaced apart gears to a shaft; blockers engaged in response to a pre-energizer effecting initial engagement of the friction members in response to initial engaging movement of one of the jaw members by a shift force, the blockers being operative to prevent asynchronous engagement of the jaw members and to transmit the shift force to the friction members to increase synchronizing torque thereof, and self-energizing ramps reacting the torque to provide an additional force in the direction of and additive to the shift force for further increasing the synchronizing torque of the friction members. A pin-type synchronizer mechanism employing the invention herein may or may not include self-energizing ramps.
Many pin-type synchronizer mechanisms include rings having cone friction surfaces that are axially movable from a neutral position of the synchronizer mechanism into mating engagement with cone friction surfaces defined by members affixed against rotation and all axial movement relative to the gears.
Such axial affixing of the members is preferred to ensure clearance between the friction surfaces when the synchronizer mechanism is in neutral, to ensure disengagement of the surfaces when the synchronizer mechanism is moved from an engaged position to neutral position, ensure or mitigate inadvertent engagement of self-energizing ramps due to, for example, viscous shear drag of oil between the friction surfaces producing a torque, etc.
In some transmission installations, it is difficult and/or cost prohibitive to axially affix some of the members to the gears. The invention disclosed herein negates the need to affix the members against all axial movement. The invention also ensures the above mentioned clearance, disengagement and mitigation of viscous shear drag in the event of failure of other means used to initially axially affix the members to the gears.